White Denim were just a few minutes into their sweaty Lockn’ set when their true interlocking moment took place. It was a hot, late August afternoon in Arrington, Va., and, despite their status as event newcomers and something of scene outliers, the Austin, Texas garage act already had a pretty good read on their festival crowd. So, with temperatures pushing toward 100, they brought out Joe Russo’s Almost Dead/WOLF! guitarist Scott Metzger for a run through the new boogie “Ha Ha Ha Ha (Yeah)” and their debut take on the Roxy Music Casablanca meditation “2HB.” Though it was the first time that Metzger, a mainstay of the jam community that helped seed Lockn’—thanks to his time with the turn-of-the-millennium Wetlands house band RANA—sat in with White Denim, the collaboration clicked. It also helped a band whose guitar heroics and progrock vamps have long been championed by the indie-rock community reach across the aisle to the Grateful Dead family that Lockn’ has catered to since its inception.

“We are having a good time with the music right now—we improvise inside of the arrangements we create for the stage,” guitarist James Petralli says a few weeks after that breakout set, which many considered to be a weekend highlight. “Solos are different in some tunes, and we are always messing with feels, but we are not ones to hang around in a vamp for too long.” While White Denim have specialized in subtle changes and lightning quick turns for a decade, their past year has been a time of personal reevaluation and sonic rediscovery. In March, the quartet released the Ethan Johns-produced LP Stiff on Downtown, their seventh album and first since guitarist Austin Jenkins and founding drummer Josh Block split with the band, following their work on R&B crooner Leon Bridges’ smash debut, Coming Home. Stiff also marks the first time that White Denim has enlisted a single outside producer for an entire recording process, which resulted in one of the group’s most retro-sounding releases and also perhaps their most fun and soulful. Both a rebirth and a bridge, Stiff features new guitarist Jonathan Horne and drummer Jeff Olson, veterans of Petralli’s Bop English solo project. However, as Petralli and longtime bassist Steve Terebecki have continued to fine-tune their sound throughout 2016, they’ve since reconfigured their band to instead include keyboardist/ trumpeter Mike St. Clair and drummer Jordan Richardson, a veteran of Ben Harper and Relentless7.

“The changes from night to night are probably fairly subtle to an audience,” Petralli admits. “We like to push ourselves physically and present an intense and tight show. We connect the tunes and kick the tempos up a few clicks for the stage.”

White Denim first crossed paths with Johns—whose credits include fellow modern roots acts like Ryan Adams, Kings of Leon and Ray LaMontagne, as well as legends like Paul McCartney, Tom Jones and Crosby, Stills and Nash—at a festival a few years ago and they immediately bonded. In the past, the group has favored self-production or working with multiple voices on their studio projects, but this time the band decided to hand over the reins and create a looser, more live-sounding record.

“We wanted to have a producer to take off some of the heat,” Petralli says. “In the past, it got a little confusing for us with the give and take of everybody producing together, so having a centralized guy in that leadership role was something we were interested in.”

The group stuck to their usual, organic formula, with Petralli crafting most of Stiff's verses, chords and lyrical changes and the rest of the band writing their parts and coming up with the arrangements as a unit. “If it sounds like the best Justin Bieber song ever, it’s definitely going to make the record,” Petralli says with a sly grin.

Terebecki, who is usually the second person to take a crack at the songs, thinks the record’s loose feel is a result of Johns’ decision to record Stiff live to 16-track. “We didn’t have a lot of opportunity to add a lot of overdubs,” he says. “So we played live as a four-piece and that’s how the record is, outside of a couple overdubs here and there.”

It's a rainy April afternoon and Petralli and Terebecki are sitting at a high-top in a Lower East Side New York City bar next door to the indie-rock incubator Bowery Ballroom. They are both dressed in the same clothes they’ll sport onstage a few hours later. Petralli, whose father and grandfather both played professional baseball, is wearing a backward cap and a jean jacket with a pack of cigarettes tucked into his front pocket. Terebecki is in a fitted white shirt with some tie-dye flourishes.

White Denim is in the midst of a packed two-night run at the club, which has hosted several of the band’s career-defining shows in recent years. In 2013, they even played a double-header that stretched late into the night and, as much as anything, showcased their ability to harness the DIY energy of the city’s rowdy livemusic freaks. While picking at a plate of nachos, White Denim’s principal members are discussing their take on Steely Dan’s “Peg,” which is the first cover they’ve added to their repertoire. Terebecki says they adopted the song at the request of a Jimmy Kimmel Live! staffer who agreed to book the group if they learned the Steely Dan classic. Since then, they’ve also dropped in a Prince tribute medley. (Improv-rock troubadour, and the evening’s opening act, Sam Cohen sat in regularly on both selections throughout the tour and also introduced them to Metzger, who joined them for their Roxy Music nod.)

White Denim has been the musicians’ primary musical outlet since 2005, when Terebecki’s band Peach Train shared a bill with fellow Austin act Parque Touch, which featured Block, Petralli and guitarist Lucas Anderson. Terebecki was invited to join Parque Touch and, after trying out a few different names, the group started gigging around their hometown as White Denim in 2006. (Anderson left the band to move to Russia.) They quickly settled on their signature blend of prog-rock technicality and loose, garagerock swagger. From the start, Petralli served as the band’s frontman, honing his bluesy voice to give the group’s songs weight, but with a delivery that still kept things fun enough to hint at his Frank Zappa obsession. The rhythm section of Terebecki and Block was equally dexterous, allowing the trio to move as a unit and spike their songbook with elements of jazz, psychedelia and ‘70s stoner rock. A few choice spots at SXSW, CMJ and, especially, Austin City Limits Music Festival, as well as their initial full-length release, Workout Holiday, introduced their punky yet experimental sound.

Petralli and Terebecki both note their ties to the improvisational world. Terebecki’s dad was a Dead fan who also listened to a lot of “prog and periphery jambands like Ozric Tentacles around the house,” he says.

His bandmate’s roots run even deeper. “I’ve always been a really big fan of Jerry Garcia as a guitar player, so I cop a lot of his moves,” Petralli says with a smile. “I had a good friend who could drive before me, and his older brother was really into [Widespread Panic’s] Space Wrangler, The Black Crowes, Traffic and classic rock. That’s all we would listen to. I saw Panic a couple times and smoked opium out of a deer antler at one of their shows—I was 17, so it was pretty informative, and I just got into smoking grass and listening to extended guitar solos. My senior year of high school, I saw Phish a bunch of times around Farmhouse.”

As his tastes changed, Petralli started digging into the Thrill Jockey catalog, falling under the spell of experimental post-rock acts like Tortoise and exploring good old-fashioned rock-and-roll. “I stepped away from the scene a little bit, but I always loved the studio records of the Grateful Dead,” Petralli says, pegging himself as a child of the modern jamband era. “The more time I spend in the studio, the more I love those records and appreciate what they accomplished from a production and writing standpoint. Those are still some of the most creative recordings ever made.”